• Macromolecular Research
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• 제14권3호
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• pp.338-342
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• 2006

The kinetic features of polymerization with an active site comprising cobalt dihalides ($CoX_2$, where X=Cl, Br, I) activated by methylaluminoxane (MAO) were investigated in 1,3-butadiene polymerization. The catalytic system exhibited the characteristic features of living polymerization. The initiation ($k_i$) and propagation ($k_p$) rate coefficients were estimated using the kinetic model for slow initiation previously reported by Shiono et al. The energy of activation fur the propagation reaction was calculated to be 27-30 $kJmol^{-1}$. The marked changes in reaction rate observed with different halides could be adequately described in terms of variations in the initiation process, with the same Arrhenius curve fitting propagation rate coeffcients estimated from all three halides, suggesting that the halide does not participate in the growing chain end.

• Food Science and Biotechnology
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• 제14권1호
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• pp.152-163
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• 2005

Lipid peroxidation is a primary cause of quality deterioration in meat and meat products. Free radical chain reaction is the mechanism of lipid peroxidation and reactive oxygen species (ROS) such as hydroxyl radical and hydroperoxyl radical are the major initiators of the chain reaction. Lipid peroxyl radical and alkoxyl radical formed from the initial reactions are also capable of abstracting a hydrogen atom from lipid molecules to initiate the chain reaction and propagating the chain reaction. Much attention has been paid to the role of iron as a primary catalyst of lipid peroxidation. Especially, heme proteins such as myoglobin and hemoglobin and "free" iron have been regarded as major catalysts for initiation, and iron-oxygen complexes (ferryl and perferryl radical) are even considered as initiators of lipid peroxidation in meat and meat products. Yet, which iron type and how iron is involved in lipid peroxidation in meat are still debatable. This review is focused on the potential roles of ROS and iron as primary initiators and a major catalyst, respectively, on the development of lipid peroxidation in meat and meat products. Effects of various other factors such as meat species, muscle type, fat content, oxygen availability, cooking, storage temperature, the presence of salt that affect lipid peroxidation in meat and meat products are also discussed.

• Elastomers and Composites
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• 제40권1호
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• pp.3-11
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• 2005

시차열분석계(DSC)를 이용하여 달린(pendant) 탄소카본길이가 8(C-8), 12(C-12), 16(C-16)인 3 가지 종류의 무수화물(ASA)과 두 가지 촉매를 이용한 에폭시 수지의 경화 동력학을 연구하였다. 비등온(Nonisothermal)과 등전환(Isoconversional)법을 사용하였다. 비등온법의 결과는 무수화물의 달린 카본길이에 따른 결과에는 큰 차이가 없었다. 그러나 등전환법에서는 촉매사용에 따라 개시반응의 활성화 에너지가 C-8, C-12, 그리고 C-16의 경우 각각 $61.7{\sim}57.7kJ/mol$, $63.0{\sim}57.3 kJ/mol$, 그리고 $130.4{\sim}94.2 kJ/mol$이었다. 보고된 개시반응의 활성화에너지 20 kJ/mol 과 다른 것은 무수화물의 달린 탄소길이에 따른 효과로 해석된다.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2002년도 Current Trends in Toxicological Sciences
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• pp.89-89
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• 2002

It is well known that oxygen radicals induce neuronal cell damage by initiation of lipid peroxidation chain reaction. Recent work has been also demonstrated that enzymatically generated free radicals cause the release of glutamate and aspartate from cultured rat hippocampal slices.(omitted)

• 한국광학회지
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• 제2권4호
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• pp.227-232
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• 1991

The possibility for the high intensity and energy possessing a short pulse in the HF chemical laser system which contained fluoride molecules (RF) was demonstrated theoretically through the numerical model simulation. The calculation was accomplished by assuming that the thermal branched chain mechanism of RF was occurred in the initiation step of $H_2+F_2$ chain reaction. Variations of the major chemicals and the temperature in the system were calculated as a function of time. An analysis was also performed to evaluate output pulse profile through parametric studies.

• 공업화학
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• 제10권3호
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• pp.432-437
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• 1999

폴리에틸렌 열분해실험을 반응기 크기가 $10cm^3$인 스테인레스 스틸 반응기에서 수행하였으며 이때 반응온도는 $390{\sim}450^{\circ}C$이었다. 열분해생성물인 반응생성물과 기체생성물을 분리하여 채취하였고 각 생성물의 분자량분포는 HPLC-GPC와 GC분석을 통해 얻었다. 열분해반응의 개시-종료, 전파-비전파반응, 즉 수소탈취반응, 사슬절단, 고분자물질과 라디칼과의 결합반응 등을 설명할 수 있는 random, specific 생성물의 분자랑분포에 대한 distribution balance식을 제안하였다. 말단절단 과정에 의해 저분자량의 비응축성 기체생성물 (C1~C5)이 생성되었으며 이 기체생성물의 평균분자량은 38이었다. 무작위절단과 말단절단의 속도매개변수 중의 하나인 활성화에너지는 각각 35, 17 kcal/mole 이었다.

• Tuberculosis and Respiratory Diseases
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• 제78권3호
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• pp.227-231
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• 2015

Background: Diagnostic methods for pulmonary tuberculosis (TB) have recently advanced. The aim of this study was to evaluate the changes in TB diagnostic tests that prompted the initiation of anti-TB treatment over time in South Korea, an industrialized country with an intermediate TB burden. Methods: Patients diagnosed with pulmonary TB in the first halves of 2005 and 2013 at a tertiary referral hospital were included. Diagnostic methods that prompted the initiation of anti-TB treatment were compared between the 2 groups of patients. Results: A greater proportion of patients were diagnosed with pulmonary TB using bronchoscopy in 2013 than in 2005 (26.7% vs. 6.6%, respectively; p<0.001), while the proportion of patients clinically diagnosed with pulmonary TB was lower in 2013 than in 2005 (24.7% vs. 49.0%, respectively; p<0.001). Additionally, more patients started anti-TB treatment based on positive polymerase chain reaction (PCR) results for Mycobacterium tuberculosis DNA in 2013 than in 2005 (47.3% vs. 7.9%, respectively; p<0.001). Conclusion: The initiation of treatment for pulmonary TB in South Korea has become more frequently based on PCR and the use of bronchoscopic specimens.

• Biomolecules & Therapeutics
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• 제16권3호
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• pp.184-189
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• 2008

The proto-oncogene protein DEK has been implicated in various human disease including cancer. We have shown that DEK induces caspase-dependent apoptosis in Drosophila by regulating histone acetylation. Reverse transcription-polymerase chain reaction (RT-PCR) method based on annealing control primers was used to screen and identify differentially expressed genes (DEGs) in DEK overexpressed HeLa cells. Among the genes identified, clusterin and fibrillarin have major role in apoptosis pathway regulation. TFIIIC and RPS24 are implicated in HAT mediated transcriptional initiation and cololectal cancer, respectively. To further analyze DEK's role in apoptosis, multiplex PCR was performed. Caspase-3, -7, and -10 and proapoptotic gene bid were newly identified as possible target genes regulated by DEK expression.

• Journal of Microbiology
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• 제34권3호
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• pp.236-240
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• 1996

Rifampin is the most powerful drug for treating leprosy and tuberculosis today. It inhibits initiation and elongation of RNA transcription by binding to $\beta$-subunit of RNA polymerase, leading to kill mycobacteria. We isolated one variant strain of Mycobacterium leprae from 24 Korean leprosy patients who are less susceptible to rifampin or have suffered from relapse by polymerase chain reaction and single strand conformation polymorphism (PCR-SSCP) of the rpoB gene. Direct sequencing of the rpoB region of M. leprae variant revealed missense mutations which altered the amino acids sequenceof RpoB to Ser-464, Arg-465, Arg-467 and Ala-468. This is the first finding on rpoB gene mutation of M. leprae from Korean patients ; moreover the mutant type was found to be different from the previously reported cases in other countries.

• 생명과학회지
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• 제8권4호
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• pp.360-365
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• 1998

The genetic of a recently described virus, hepatitis G virus(HGV) was investigated. HGV envelope 1 (E1) nucleotide sequences isolated from six Korean hepatitis b virus-positive patients by using a reverse transcription-poly-merase chain reaction procedure, were analysed and compared to the seven previously reported HGV isolates. Sequence homology among the Korean isolates was 88-97% whereas among the isolates from different geographic areas was 80-92%, indicating geographical divergence of HGV. Nucleotide substitutions spread uniformly throughiut the E1 fragment. Furthermore, compared to the prototype HGV sequence, frameshift mutations were observed in most of the Korean isolating that a different translating initiation site for the polyprotein exists in the Korean type HGV.